1. Field of the Invention
This invention relates generally to a method and system for identifying cell monitoring controllers in a battery pack and, more particularly, to a method and system for identifying cell monitoring controllers in an electric or hybrid vehicle battery pack which uses a multi-purpose signal line to activate and identify each cell monitoring controller in sequence, thus allowing use of identical controllers throughout the battery pack.
2. Discussion of the Related Art
Electric vehicles and gasoline/electric hybrid vehicles are rapidly gaining popularity in today's automotive marketplace. Electric and hybrid vehicles offer several desirable features, such as reduced emissions, reduced usage of petroleum-based fuels, and potentially lower operating costs. A key component of both electric and hybrid vehicles is the battery pack. Battery packs in these vehicles typically consist of numerous interconnected cells, operating at a relatively high voltage, and delivering a lot of power on demand. In order to maximize vehicle driving range and maximize battery pack life, the cells in the battery pack must be controlled during charging and discharging so that all cells are maintained at a fairly uniform charge level.
In order to monitor and control the charging and discharging of the cells in the battery pack, cell monitoring controllers are used. Because of the physical size of battery packs in electric and hybrid vehicles, several cell monitoring controllers are often needed, where each controller has responsibility for a number of cells in the battery pack. In such a configuration, a master battery pack controller is used to communicate with the multiple cell monitoring controllers. For this arrangement to be effective, it is necessary for the master battery pack controller to be able to identify each of the cell monitoring controllers, and for the cell monitoring controllers in turn to be able to index each cell in the battery pack. The need to uniquely identify each cell monitoring controller has traditionally been met by uniquely configuring each cell monitoring controller in the battery pack, where the unique configuration could be accomplished with hardware or software in the cell monitoring controllers. But making each cell monitoring controller unique has the dual disadvantage of preventing use of a common part for all cell monitoring controllers in the battery pack, and also adding complexity to manufacturing and service operations which must then carefully distinguish between identical-looking parts.
There is a need for an improved method of identifying individual cell monitoring controllers in a battery pack which does not require each controller to be uniquely configured. Such a method could yield cost savings for manufacturers of electric and hybrid vehicles, through part number reduction, increased volume for a common part, and simplification of manufacturing and service operations.